Holloway. — The Prothallus and Young Plant of Tmesipteris. 31 



and 65, in which the differentiation of vascular tissue between the shoot- 

 apex and the foot would be in its earliest stages. Transverse sections 

 of plantlets of the same age as that shown in fig. 68 are given in figs. 78, 

 79, and 80 There is a slight central strand consisting of, in the one 

 case, one, and, in the other, two, narrow scalariform tracheides placed 

 more or less collaterally with a group of darkly-staining phloem elements. 



Fig. 76. — Longitudinal section of apex of rhizome of young plant shown in fig. 5, showing 



single apical cell. X 140. 

 Fig 77. — Longitudinal section of apex of aerial stem of young plant shown in fig. 5, 



showing single apical cell. X 140. 

 Fig. 78. — Transverse section of stem of young plant similar to those shown in 



figs. 66-68. X 50. 

 Fig. 79. — Transverse section of stele of stem shown in fig. 78. X 200. 

 Fig. 80. — Transverse section of stem stele of another young plant. X 200. 



There is an endodermis in which the characteristic radial markings are 

 clear. The cortex is uniformly parenchymatous and harbours the fungal 

 coils more especially in its middle zone, whilst the epidermis is cuticularized 

 and individual epidermal cells are prolonged into rhizoids. Longitudinal 

 sections of a young prothallial plantlet similar to that shown in fig. 68 

 revealed the fact that the vascular strand of the shoot curved bodily 

 round at the base of the plant into the foot, where it ended blindly. From 



